Bridge



3 Sheets-Sheet 1 A. PINK.

. THU-SS BRIDGE.

THE NORRIS PETERS m. moTo-Lrruu. wasummm a, c,

3 Sheets-Sheet 3; PINK. ,1 TRUSS BRIDGE.

Patented May 9, 18 54.

llahl.

IBBIDGE.,

To al/ll whom z't. may concern f Be itlknown that I, ALBnR'r Finn, of the city of Baltimore and State of Maryland,

have invented a new and useful 3 Improve-z ment in Bridge-Trusses; and IndO hereby declare that the following is a fulhclear,

andfie xact. description of the construction and operation ofthe same, reference being had to the annexed drawings, forming part ofthis specification, in which 1 1 *Plate 1 shows the application of my improvement Ito] bridges where the roadway is above the truss, Figure '1. representing a side elevation. Fig.2 a plan. Fig. 3 a cross section and Figs. at to 15 detailsofdifierent A parts. :Plate12shows the application ofmy improvement tobridges where theztruss is.

above the roadway, Fig. 1 representing a diagram of the-whole truss; FFig. 25' an ele-.

vation "of a part of the truss. Fig. 3 :a plan of thewtop of thatpartLFigrd a .plan of floor. Fig. 5a-lfront view.q. Fig. '6-a cross section and Figs. .to .13 1 details of the bridge... 1

4 (In each. plate letters 0t reference in the-several figures denote the same part of the bridge;

The nature of my invention consists. in combining difl'erent. systems of triangular bracings in the manner hereafter to the described, so that a weight coming on one of the systems of the truss is not only carried over one or more other systems before it is carried back to the abutment, but the foot of the post of each triangle shall be capable of settling vertically or moving to the side, so that the tension rods of each system of the triangular bracings will be strained equally when the bridge settles under a superincumbent Weight.

To enable others skilled in the art to use my invention I will proceed'to describe the same, and its operation.

In Plate 1, A A represent stretchers of their heads or ends resting on the abutments W. The middle point of the. stretcher A (see Fig. 1 Plate 1) I support by the suspension bars B B through the post C, the details of the connection between the stretcher A, 0st 0, and suspension bars B B being set orth in the drawing, and not being essential to the understanding of the invention, will not require here any particular description. I then by suspension Specification ofiIlettersPatent No. 10,887, dated May 9,, 1854.

irods B B and postsc support. two points intermediate between the central: point and. the .abutments, forming the second triangularsystemsa Then by rodsnB .B'f and posts C I support four points between the Zabutments, posts.C,-andpost C; forming gthe third triangular systems, and in. this. imannerI multiply the systemsaccording to tthe span of the bridge,supporting first the ;central point by suspension rods runningto {the abutments, then making this central point a point of supportifor twoother sys+ items, which intermediate points in their turn. may become points: of supportfor other; sysg terns.

1 Plate 2 shows myinventionas. appliedutoa jbridgeswith the. truss above the roadway iwhere BB is the; first system ot-suspension, rods,.B B the second systemyBf B thethird system, andhsoon the several systems, Zbeing distinctly shown by the various jCOl; Eored lines in =Fig. 1 of that plate. t l Thepperation of myimproved truss isias. lfollows: The pressure of a load at anypointv got the truss, is;diifused over the entire truss iand, transmittedthrough; one or more ofthe 3 1 various systems of which the truss is com= iposed beforebeing carried to the ahutmentss For instance a .pressure coming (upon the lbridgeX" Fig. 1-P1-ate 1, will be; received by system 3 and a portion of that pressure transmitted by suspension rods B to system 2, and a portion from thence by rod B to system 1, whence by suspension rods B B, it is carried to the abutments; the weight having been diffused over the entire span. The operation will be the same no matter how many triangular systemsmay be used in the truSS.

The sinking of a-portion of the truss by a superincumbent weight, or by changes in the condition of the materials used in construction from effects of temperature, will not cause the several parts of the truss to deviate from their mutual adjustments, as will readily be seen by reference to diagram X Plate 1, where the point a of system 1 settles as indicated by the red letter a; the two triangles of system 2 will change their position as shown by the red lines 2 2, the points I) b of systems 2 not only settling vertically but moving horizontally as indicated. in the diagram. Now although the position of the triangles of system 2 has changed, there have been no changes in the triangles themselves, and therefore their bearing capacity is still the same as it was before the settling "of the point a. What is here illus-- foot of the post in the 2d system to rest upon:

the tension chord of the post of the first sys tem as heretofore used; the freedom. of

movement allowed to the foot of the post of each system producing the beneficial vresult due to myinvention. v

The constructions set forth in the drawings are but two of the applications of my invention, and mustnot be considered as confining it in any respect, as any suitable material maybe used in construction, and a great variety of forms given to the parts. The stretchers may be octagon, square, roundaor of any other form, and either of wood or cast ironij The posts may be of any desired form of cross section; and the suspension bars' maybe either wire cables, or wrought iron bars. Moreover upright trusses may beconstructed as above described for inverted ones by the substitution of struts for suspension bars, ties for the stretchers, and suspension rods for the posts; the same laws governing the combination in this case as will obtain in the cases described." a Y The points supported need'not necessarily be arranged and chosen as above set forth, the general rule being to support a point at or nearthe middle of" the span by system 1, the first intermediate points'by system 2, whether these points are in the middle, be-

angular bracings, in such a manner, that one system of triangles is supported by and dependent on the other, merely, as I am aware that this has been done before, both in trusses for bridges and roofs. But

What I do claim as of my own invention,

and as difierent from any other method of bracing and strengthening bridge trusses heretofore known, is

The method of combining the difierent systems of triangular bracings, above described, so that a weight coming on one of the systems of the truss, is notonly transferred over one or more other systems, before it is carried back to the abutments; but

the foot of the post in each triangle, being unconnected with the tension rods of the other triangular bracings, can settle ,vertically, as well as move to the side; so that the tension rods of eachsystem of the triangular bracings will be strained equally,

when the bridge settles under a superin v cumbent weight. This would not be the case, if the foot of the post in the 2d system of triangular bracings rested on the tension chord of the post, in the first system, as heretofore used; and herein consists my improvement, for which I ask Letters Patent.

ALBERT FINK.

Witnesses:

J os. T. ATKINSON, R. VAN WINKLE. 

